Photodynamic therapy (PDT) can be an effective anticancer treatment option. PDT involves the administration of a tumor-localizing photosensitizer (PS) followed by light activation to generate highly cytotoxic reactive oxygen species (ROS), particularly singlet oxygen (1O2), which trigger cell apoptosis and necrosis. By localizing both the PS and the light exposure to tumor regions, PDT can selectively kill tumor cells while preserving local tissues. PDT has been used to treat patients with many different types of cancer, including head and neck tumors, breast cancer, gynecological tumors, brain tumors, colorectal cancer, mesothelioma, and pancreatic cancer. The use of PDT for treating cancers in the head and neck is particularly advantageous over traditional treatment modalities, e.g., surgery and irradiation, as PDT causes less destruction of surrounding tissues and reduces aesthetic and functional impairments. Porphyrin molecules such as PHOTOFRIN®, VERTEPORFIN®, FOSCAN®, PHOTOCHLOR®, and TALAPORFIN® are among the most commonly used PSs for PDT. However, although they have efficient photochemistry for ROS generation, their suboptimal tumor accumulation after systemic administration can limit the efficacy of PDT in the clinic.
Accordingly, there is an ongoing need for additional delivery vehicles for improving the delivery (e.g., the targeted delivery) of PS therapeutics. In particular, there is a need for delivery vehicles that can deliver PSs in combination with other therapeutics (e.g., other chemotherapeutics and immunotherapy agents) in order to increase treatment efficacy.